Pinealon

Pinealon is a synthetic tripeptide, Glu-Asp-Arg, from the Khavinson short-peptide bioregulator programme. The programme is associated with the St Petersburg Institute of Bioregulation and Gerontology, and the literature also refers to this peptide by its three-letter code EDR.

The sequence is confirmed from three independent directions rather than from vendor copy, which for this class of compound is unreliable: the US patent application 2012/0309688A1 claims the peptide as H-Glu-Asp-Arg-OH, the NLM MeSH supplementary concept record C570174 gives Pinealon and glutamyl-aspartyl-arginine as entry terms for the same substance, and Khavinson's own 2021 review in Molecules lists EDR under this name.

Both termini are unmodified: a free N-terminal amine and a free C-terminal carboxyl. The formula and mass above are for that free acid, as registered at PubChem CID 10273502 and stated independently in the patent. The isolated substance described in the patent is an acetate ion pair, and no primary source states the acetate stoichiometry, so a mass quoted for the salt cannot be derived from the figure here.

There is no tryptophan, tyrosine or phenylalanine, which means there is no chromophore at 280 nm. The patent's own analysis reflects that: its chromatography is run at 220 nm, where the peptide bond absorbs, rather than at the wavelength an aromatic residue would provide. There is no cysteine and no methionine, so there is no oxidation-prone side chain at all.

Its molecular work is nucleic-acid binding rather than receptor binding, and no receptor has been identified. Fedoreyeva and colleagues, in Biochemistry (Moscow) in 2011, followed a fluorescently labelled peptide into the cytoplasm, nucleus and nucleolus of HeLa cells and measured Stern-Volmer quenching constants against labelled deoxyribooligonucleotides, reporting preferential binding to CAG-containing sequences and discrimination of cytosine methylation state. Silanteva and colleagues, in the Journal of Physical Chemistry B in 2019, used ultraviolet spectroscopy, NMR, viscosimetry and molecular dynamics to place the peptide partly inside the DNA major groove contacting the N7 and O6 atoms of guanine, with magnesium strengthening the interaction by screening phosphate charge.

It also appears in transporter docking work: Khavinson and colleagues, in Biomolecules in 2023, scored it as the best-ranked ligand of LAT1 and PEPT1 among twenty-six ultrashort peptides. That is a computational result and is stated as one.